Multi-group call setup method and device

ABSTRACT

A multi-group call setup method and device are disclosed. The method includes determining, by a first MCPTT server, to set up a multi-group call involving N MCPTT groups, where N is an integer greater than or equal to 2, and sending, by the first MCPTT server, a call message to first UE, where the call message is used to add the first UE to the multi-group call, where a first MCPTT user is an associated user of the first UE, and where the first MCPTT user is an MCPTT user in the N MCPTT groups.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Application No.PCT/CN2015/076144, filed on Apr. 9, 2015, the disclosure of which ishereby incorporated by reference in its entirety.

TECHNICAL FIELD

Embodiments of the present invention relate to the field ofcommunications technologies, and in particular, to a multi-group callsetup method and device.

BACKGROUND

In practical application, there is a requirement that an authorizedmission critical push to talk (MCPTT for short) user may need toinitiate a group call involving multiple MCPTT groups. For example, insome emergencies, fire brigades and police forces cooperate with eachother. Because an on-site commander may need to coordinate actions ofmultiple MCPTT groups to deliver a same instruction and task, a callinvolving the multiple MCPTT groups is initiated. In the prior art, sucha function of a multi-group call cannot be supported yet.

SUMMARY

Embodiments of the present invention provide a multi-group call setupmethod and device, to perform a multi-group call among multiple MCPTTgroups.

According to a first aspect, an embodiment of the present inventionprovides a multi-group call setup method, including determining, by afirst MCPTT server, to set up a multi-group call involving N MCPTTgroups, where N is an integer greater than or equal to 2, and sending,by the first MCPTT server, a call message to first user equipment (UEfor short), where the call message is used to add the first UE to themulti-group call, where a first MCPTT user is an associated user of thefirst UE, and the first MCPTT user is any MCPTT user in the N MCPTTgroups.

With reference to the second aspect, in a first possible implementationmanner of the first aspect, before the determining, by a first MCPTTserver, to set up a multi-group call involving N MCPTT groups, themethod further includes receiving, by the first MCPTT server, amulti-group call setup message sent by second UE, where the multi-groupcall setup message is used by a second MCPTT user to request the firstMCPTT server to set up the multi-group call involving the N MCPTTgroups, the second MCPTT user is an associated user of the second UE,and an MCPTT group to which the second MCPTT user belongs is at leastone of the N MCPTT groups, and the determining, by a first MCPTT server,to set up a multi-group call involving N MCPTT groups includesdetermining, by the first MCPTT server according to the multi-group callsetup message, to set up the multi-group call, where the first MCPTTuser is any MCPTT user in the N MCPTT groups except the second MCPTTuser.

With reference to the first possible implementation manner of the firstaspect, in a second possible implementation manner of the first aspect,the multi-group call setup message includes an identifier of a temporarygroup that includes the N MCPTT groups, and the first MCPTT server is anMCPTT server of the temporary group.

With reference to the second possible implementation manner of the firstaspect, in a third possible implementation manner of the first aspect,the receiving, by the first MCPTT server, a multi-group call setupmessage sent by second UE includes receiving, by the first MCPTT server,the multi-group call setup message that is sent by the second UE andthat is forwarded by an MCPTT server of the second MCPTT user.

With reference to the second possible implementation manner of the firstaspect or the third possible implementation manner of the first aspect,in a fourth possible implementation manner of the first aspect, beforethe sending, by the first MCPTT server, a call message to first UE, themethod further includes obtaining, by the first MCPTT server,information about the temporary group according to the identifier of thetemporary group, where the information about the temporary groupincludes the identifier of the temporary group and identifiers of the NMCPTT groups.

With reference to the fourth possible implementation manner of the firstaspect, in a fifth possible implementation manner of the first aspect,the information about the temporary group further includes informationabout an MCPTT user in at least one of the N MCPTT groups.

With reference to the first possible implementation manner of the firstaspect, in a sixth possible implementation manner of the first aspect,the multi-group call setup message includes identifiers of the N MCPTTgroups, and the first MCPTT server is an MCPTT server of the secondMCPTT user.

With reference to the sixth possible implementation manner of the firstaspect, in a seventh possible implementation manner of the first aspect,before the sending, by the first MCPTT server, a call message to firstUE, the method further includes obtaining, by the first MCPTT server,information about an MCPTT user in at least one of the N MCPTT groupsaccording to the identifiers of the N MCPTT groups.

With reference to any one of the first aspect, or the first to theseventh possible implementation manners of the first aspect, in aneighth possible implementation manner of the first aspect, the sending,by the first MCPTT server, a call message to first UE includes sending,by the first MCPTT server, a first paging message to the first UE, wherethe first paging message is used to page the first UE to join themulti-group call, so that the first UE joins the multi-group callaccording to the first paging message.

With reference to any one of the first aspect, or the first to theseventh possible implementation manners of the first aspect, in a ninthpossible implementation manner of the first aspect, the sending, by thefirst MCPTT server, a call message to first UE includes sending, by thefirst MCPTT server, a second paging message to an MCPTT server of thefirst MCPTT user, where the second paging message is used to page thefirst UE to join the multi-group call, so that the MCPTT server of thefirst MCPTT user sends a third paging message to the first UE, and thefirst UE joins the multi-group call according to the third pagingmessage.

With reference to any one of the first aspect, or the first to theseventh possible implementation manners of the first aspect, in a tenthpossible implementation manner of the first aspect, the sending, by thefirst MCPTT server, a call message to first UE includes sending, by thefirst MCPTT server, a fourth paging message to an MCPTT server of anMCPTT group to which the first MCPTT user belongs, where the fourthpaging message is used to page the first UE to join the multi-groupcall, so that the MCPTT server of the MCPTT group to which the firstMCPTT user belongs sends a fifth paging message to the first UE or sendsa fifth paging message to the first UE by using an MCPTT server of thefirst MCPTT user, and the first UE joins the multi-group call accordingto the fifth paging message, where the fifth paging message is used topage the first UE to join the multi-group call.

With reference to any one of the first aspect, or the first to theseventh possible implementation manners of the first aspect, in aneleventh possible implementation manner of the first aspect, thesending, by the first MCPTT server, a call message to first UE includessending, by the first MCPTT server, a first notification message to thefirst UE, where the first notification message includes a sessionidentifier of the multi-group call, and the first notification messageis used to instruct the first UE to join the multi-group call accordingto the session identifier, so that the first UE joins the multi-groupcall according to the session identifier.

With reference to any one of the first aspect, or the first to theseventh possible implementation manners of the first aspect, in atwelfth possible implementation manner of the first aspect, the sending,by the first MCPTT server, a call message to first UE includes sending,by the first MCPTT server, a second notification message to an MCPTTserver of the first MCPTT user, where the second notification messageincludes a session identifier of the multi-group call, and the secondnotification message is used to instruct the first UE to join themulti-group call according to the session identifier, so that the MCPTTserver of the first MCPTT user sends a third notification message to thefirst UE, where the third notification message includes the sessionidentifier, and the third notification message is used to instruct thefirst UE to join the multi-group call according to the sessionidentifier, so that the first UE joins the multi-group call according tothe session identifier.

With reference to any one of the first aspect, or the first to theseventh possible implementation manners of the first aspect, in athirteenth possible implementation manner of the first aspect, thesending, by the first MCPTT server, a call message to first UE includessending, by the first MCPTT server, a fourth notification message to anMCPTT server of an MCPTT group to which the first MCPTT user belongs,where the fourth notification message includes a session identifier ofthe multi-group call, and the fourth notification message is used toinstruct the first UE to join the multi-group call according to thesession identifier, so that the MCPTT server of the MCPTT group to whichthe first MCPTT user belongs sends a fifth notification message to thefirst UE or sends a fifth notification message to the first UE by usingan MCPTT server of the first MCPTT user, and the first UE joins themulti-group call according to the session identifier.

According to a second aspect, an embodiment of the present inventionprovides a multi-group call setup method, including receiving, by firstUE, a call message, where the call message is used to add the first UEto a multi-group call involving N MCPTT groups, N is an integer greaterthan or equal to 2, a first MCPTT user is an associated user of thefirst UE, and the first MCPTT user is any MCPTT user in the N MCPTTgroups; and joining, by the first UE, the multi-group call according tothe call message.

In a first possible implementation manner of the second aspect, thereceiving, by first UE, a call message includes receiving, by the firstUE, a notification message, where the notification message includes asession identifier of the multi-group call, and the notification messageis used to instruct the first UE to join the multi-group call accordingto the session identifier; and the joining, by the first UE, themulti-group call according to the call message includes joining, by thefirst UE, the multi-group call according to the session identifier.

With reference to the second aspect or the first possible implementationmanner of the second aspect, in a second possible implementation mannerof the second aspect, the multi-group call involving the N MCPTT groupsis initiated by a second MCPTT user, and the first MCPTT user is anyMCPTT user in the N MCPTT groups except the second MCPTT user.

With reference to the second aspect, the first possible implementationmanner of the second aspect, or the second possible implementationmanner of the second aspect, in a third possible implementation mannerof the second aspect, the receiving, by first UE, a call messageincludes receiving, by the first UE, the call message that is sent by anMCPTT server of an MCPTT group to which the first MCPTT user belongs, orreceiving, by the first UE, the call message that is sent by an MCPTTserver of the first MCPTT user, or receiving, by the first UE, the callmessage that is sent by an MCPTT server of a temporary group thatincludes the N MCPTT groups.

With reference to the second possible implementation manner of thesecond aspect, in a fourth possible implementation manner of the secondaspect, the receiving, by first UE, a call message includes receiving,by the first UE, the call message that is sent by an MCPTT server of thesecond MCPTT user.

According to a third aspect, an embodiment of the present inventionprovides a multi-group call setup method, including generating, bysecond UE, a multi-group call setup message, where the multi-group callsetup message is used by a second MCPTT user to request a first MCPTTserver to set up a multi-group call involving N MCPTT groups, N is aninteger greater than or equal to 2, the second MCPTT user is anassociated user of the second UE, and an MCPTT group to which the secondMCPTT user belongs is at least one of the N MCPTT groups; and sending,by the second UE, the multi-group call setup message to the first MCPTTserver.

With reference to the third aspect, in a first possible implementationmanner of the third aspect, the multi-group call setup message includesan identifier of a temporary group that includes the N MCPTT groups, andthe first MCPTT server is an MCPTT server of the temporary group.

With reference to the first possible implementation manner of the thirdaspect, in a second possible implementation manner of the third aspect,the sending, by the second UE, the multi-group call setup message to thefirst MCPTT server includes sending, by the second UE, the multi-groupcall setup message to the first MCPTT server by using an MCPTT server ofthe second MCPTT user.

With reference to the first possible implementation manner of the thirdaspect or the second possible implementation manner of the third aspect,in a third possible implementation manner of the third aspect, beforethe sending, by the second UE, the multi-group call setup message to thefirst MCPTT server, the method further includes creating, by the secondUE, the temporary group.

With reference to the third aspect, in a fourth possible implementationmanner of the third aspect, the multi-group call setup message includesidentifiers of the N MCPTT groups, and the first MCPTT server is anMCPTT server of the second MCPTT user.

According to a fourth aspect, an embodiment of the present inventionprovides an MCPTT server, serving as a first MCPTT server and includinga processing unit, configured to determine to set up a multi-group callinvolving N MCPTT groups, where N is an integer greater than or equal to2, and a transceiver unit, configured to send a call message to firstuser equipment UE, where the call message is used to add the first UE tothe multi-group call, a first MCPTT user is an associated user of thefirst UE, and the first MCPTT user is any MCPTT user in the N MCPTTgroups.

With reference to the fourth aspect, in a first possible implementationmanner of the fourth aspect, before the processing unit determines toset up the multi-group call involving the N MCPTT groups, thetransceiver unit is further configured to receive a multi-group callsetup message sent by second UE, where the multi-group call setupmessage is used by a second MCPTT user to request the first MCPTT serverto set up the multi-group call involving the N MCPTT groups, the secondMCPTT user is an associated user of the second UE, and an MCPTT group towhich the second MCPTT user belongs is at least one of the N MCPTTgroups, and when determining to set up the multi-group call involvingthe N MCPTT groups, the processing unit is configured to determine,according to the multi-group call setup message, to set up themulti-group call, where the first MCPTT user is any MCPTT user in the NMCPTT groups except the second MCPTT user.

With reference to the first possible implementation manner of the fourthaspect, in a second possible implementation manner of the fourth aspect,the multi-group call setup message includes an identifier of a temporarygroup that includes the N MCPTT groups, and the first MCPTT server is anMCPTT server of the temporary group.

With reference to the second possible implementation manner of thefourth aspect, in a third possible implementation manner of the fourthaspect, when receiving the multi-group call setup message sent by thesecond UE, the transceiver unit is configured to receive the multi-groupcall setup message that is sent by the second UE and that is forwardedby an MCPTT server of the second MCPTT user.

With reference to the second possible implementation manner of thefourth aspect or the third possible implementation manner of the fourthaspect, in a fourth possible implementation manner of the fourth aspect,before the transceiver unit sends the call message to the first UE, theprocessing unit is further configured to obtain information about thetemporary group according to the identifier of the temporary group,where the information about the temporary group includes the identifierof the temporary group and identifiers of the N MCPTT groups.

With reference to the fourth possible implementation manner of thefourth aspect, in a fifth possible implementation manner of the fourthaspect, the information about the temporary group further includesinformation about an MCPTT user in at least one of the N MCPTT groups.

With reference to the first possible implementation manner of the fourthaspect, in a sixth possible implementation manner of the fourth aspect,the multi-group call setup message includes identifiers of the N MCPTTgroups, and the first MCPTT server is an MCPTT server of the secondMCPTT user.

With reference to the sixth possible implementation manner of the fourthaspect, in a seventh possible implementation manner of the fourthaspect, before the transceiver unit sends the call message to the firstUE, the processing unit is further configured to obtain informationabout an MCPTT user in at least one of the N MCPTT groups according tothe identifiers of the N MCPTT groups.

With reference to any one of the fourth aspect, or the first to theseventh possible implementation manners of the fourth aspect, in aneighth possible implementation manner of the fourth aspect, when sendingthe call message to the first UE, the transceiver unit is configured tosend a first paging message to the first UE, where the first pagingmessage is used to page the first UE to join the multi-group call, sothat the first UE joins the multi-group call according to the firstpaging message.

With reference to any one of the fourth aspect, or the first to theseventh possible implementation manners of the fourth aspect, in a ninthpossible implementation manner of the fourth aspect, when sending thecall message to the first UE, the transceiver unit is configured to senda second paging message to an MCPTT server of the first MCPTT user,where the second paging message is used to page the first UE to join themulti-group call, so that the MCPTT server of the first MCPTT user sendsa third paging message to the first UE, and the first UE joins themulti-group call according to the third paging message.

With reference to any one of the fourth aspect, or the first to theseventh possible implementation manners of the fourth aspect, in a tenthpossible implementation manner of the fourth aspect, when sending thecall message to the first UE, the transceiver unit is configured to senda fourth paging message to an MCPTT server of an MCPTT group to whichthe first MCPTT user belongs, where the fourth paging message is used topage the first UE to join the multi-group call, so that the MCPTT serverof the MCPTT group to which the first MCPTT user belongs sends a fifthpaging message to the first UE or sends a fifth paging message to thefirst UE by using an MCPTT server of the first MCPTT user, and the firstUE joins the multi-group call according to the fifth paging message,where the fifth paging message is used to page the first UE to join themulti-group call.

With reference to any one of the fourth aspect, or the first to theseventh possible implementation manners of the fourth aspect, in aneleventh possible implementation manner of the fourth aspect, whensending the call message to the first UE, the transceiver unit isconfigured to send a first notification message to the first UE, wherethe first notification message includes a session identifier of themulti-group call, and the first notification message is used to instructthe first UE to join the multi-group call according to the sessionidentifier, so that the first UE joins the multi-group call according tothe session identifier.

With reference to any one of the fourth aspect, or the first to theseventh possible implementation manners of the fourth aspect, in atwelfth possible implementation manner of the fourth aspect, whensending the call message to the first UE, the transceiver unit isconfigured to send a second notification message to an MCPTT server ofthe first MCPTT user, where the second notification message includes asession identifier of the multi-group call, and the second notificationmessage is used to instruct the first UE to join the multi-group callaccording to the session identifier, so that the MCPTT server of thefirst MCPTT user sends a third notification message to the first UE,where the third notification message includes the session identifier,and the third notification message is used to instruct the first UE tojoin the multi-group call according to the session identifier, so thatthe first UE joins the multi-group call according to the sessionidentifier.

With reference to any one of the fourth aspect, or the first to theseventh possible implementation manners of the fourth aspect, in athirteenth possible implementation manner of the fourth aspect, whensending the call message to the first UE, the transceiver unit isconfigured to send a fourth notification message to an MCPTT server ofan MCPTT group to which the first MCPTT user belongs, where the fourthnotification message includes a session identifier of the multi-groupcall, and the fourth notification message is used to instruct the firstUE to join the multi-group call according to the session identifier, sothat the MCPTT server of the MCPTT group to which the first MCPTT userbelongs sends a fifth notification message to the first UE or sends afifth notification message to the first UE by using an MCPTT server ofthe first MCPTT user, and the first UE joins the multi-group callaccording to the session identifier.

According to a fifth aspect, an embodiment of the present inventionprovides UE, serving as first UE and including a transceiver unit,configured to receive a call message, where the call message is used toadd the first UE to a multi-group call involving N MCPTT groups, N is aninteger greater than or equal to 2, a first MCPTT user is an associateduser of the first UE, and the first MCPTT user is any MCPTT user in theN MCPTT groups; and a processing unit, configured to join themulti-group call according to the call message.

With reference to the fifth aspect, in a first possible implementationmanner of the fifth aspect, when receiving the call message, thetransceiver unit is configured to receive a notification message, wherethe notification message includes a session identifier of themulti-group call, and the notification message is used to instruct thefirst UE to join the multi-group call according to the sessionidentifier, and when joining the multi-group call according to the callmessage, the processing unit is configured to join the multi-group callaccording to the session identifier.

With reference to the fifth aspect or the first possible implementationmanner of the fifth aspect, in a second possible implementation mannerof the fifth aspect, the multi-group call involving the N MCPTT groupsis initiated by a second MCPTT user, and the first MCPTT user is anyMCPTT user in the N MCPTT groups except the second MCPTT user.

With reference to the fifth aspect, the first possible implementationmanner of the fifth aspect, or the second possible implementation mannerof the fifth aspect, in a third possible implementation manner of thefifth aspect, when receiving the call message, the transceiver unit isconfigured to receive the call message that is sent by an MCPTT serverof an MCPTT group to which the first MCPTT user belongs, or receive thecall message that is sent by an MCPTT server of the first MCPTT user, orreceive the call message that is sent by an MCPTT server of a temporarygroup that includes the N MCPTT groups.

With reference to the second possible implementation manner of the fifthaspect, in a fourth possible implementation manner of the fifth aspect,when receiving the call message, the transceiver unit is configured toreceive the call message that is sent by an MCPTT server of the secondMCPTT user.

According to a sixth aspect, an embodiment of the present inventionprovides UE, serving as second UE and including a processing unit,configured to generate a multi-group call setup message, where themulti-group call setup message is used by a second MCPTT user to requesta first MCPTT server to set up a multi-group call involving N MCPTTgroups, N is an integer greater than or equal to 2, the second MCPTTuser is an associated user of the second UE, and an MCPTT group to whichthe second MCPTT user belongs is at least one of the N MCPTT groups, anda transceiver unit, configured to send the multi-group call setupmessage to the first MCPTT server.

With reference to the sixth aspect, in a first possible implementationmanner of the sixth aspect, the multi-group call setup message includesan identifier of a temporary group that includes the N MCPTT groups, andthe first MCPTT server is an MCPTT server of the temporary group.

With reference to the first possible implementation manner of the sixthaspect, in a second possible implementation manner of the sixth aspect,when sending the multi-group call setup message to the first MCPTTserver, the transceiver unit is configured to send the multi-group callsetup message to the first MCPTT server by using an MCPTT server of thesecond MCPTT user.

With reference to the first possible implementation manner of the sixthaspect or the second possible implementation manner of the sixth aspect,in a third possible implementation manner of the sixth aspect, theprocessing unit is further configured to create the temporary groupbefore the transceiver unit sends the multi-group call setup message tothe first MCPTT server.

With reference to the sixth aspect, in a fourth possible implementationmanner of the sixth aspect, the multi-group call setup message includesidentifiers of the N MCPTT groups, and the first MCPTT server is anMCPTT server of the second MCPTT user.

According to a seventh aspect, an embodiment of the present inventionprovides an MCPTT server, serving as a first MCPTT server and includinga processor, configured to determine to set up a multi-group callinvolving N MCPTT groups, where N is an integer greater than or equal to2; and a transceiver, configured to send a call message to first userequipment UE, where the call message is used to add the first UE to themulti-group call, a first MCPTT user is an associated user of the firstUE, and the first MCPTT user is any MCPTT user in the N MCPTT groups.

With reference to the seventh aspect, in a first possible implementationmanner of the seventh aspect, before the processor determines to set upthe multi-group call involving the N MCPTT groups, the transceiver isfurther configured to receive a multi-group call setup message sent bysecond UE, where the multi-group call setup message is used by a secondMCPTT user to request the first MCPTT server to set up the multi-groupcall involving the N MCPTT groups, the second MCPTT user is anassociated user of the second UE, and an MCPTT group to which the secondMCPTT user belongs is at least one of the N MCPTT groups, and whendetermining to set up the multi-group call involving the N MCPTT groups,the processor is configured to determine, according to the multi-groupcall setup message, to set up the multi-group call, where the firstMCPTT user is any MCPTT user in the N MCPTT groups except the secondMCPTT user.

With reference to the first possible implementation manner of theseventh aspect, in a second possible implementation manner of theseventh aspect, the multi-group call setup message includes anidentifier of a temporary group that includes the N MCPTT groups, andthe first MCPTT server is an MCPTT server of the temporary group.

With reference to the second possible implementation manner of theseventh aspect, in a third possible implementation manner of the seventhaspect, when receiving the multi-group call setup message sent by thesecond UE, the transceiver is configured to receive the multi-group callsetup message that is sent by the second UE and that is forwarded by anMCPTT server of the second MCPTT user.

With reference to the second possible implementation manner of theseventh aspect or the third possible implementation manner of theseventh aspect, in a fourth possible implementation manner of theseventh aspect, before the transceiver sends the call message to thefirst UE, the processor is further configured to obtain informationabout the temporary group according to the identifier of the temporarygroup, where the information about the temporary group includes theidentifier of the temporary group and identifiers of the N MCPTT groups.

With reference to the fourth possible implementation manner of theseventh aspect, in a fifth possible implementation manner of the seventhaspect, the information about the temporary group further includesinformation about an MCPTT user in at least one of the N MCPTT groups.

With reference to the first possible implementation manner of theseventh aspect, in a sixth possible implementation manner of the seventhaspect, the multi-group call setup message includes identifiers of the NMCPTT groups, and the first MCPTT server is an MCPTT server of thesecond MCPTT user.

With reference to the sixth possible implementation manner of theseventh aspect, in a seventh possible implementation manner of theseventh aspect, before the transceiver sends the call message to thefirst UE, the processor is further configured to obtain informationabout an MCPTT user in at least one of the N MCPTT groups according tothe identifiers of the N MCPTT groups.

With reference to any one of the seventh aspect, or the first to theseventh possible implementation manners of the seventh aspect, in aneighth possible implementation manner of the seventh aspect, whensending the call message to the first UE, the transceiver is configuredto send a first paging message to the first UE, where the first pagingmessage is used to page the first UE to join the multi-group call, sothat the first UE joins the multi-group call according to the firstpaging message.

With reference to any one of the seventh aspect, or the first to theseventh possible implementation manners of the seventh aspect, in aninth possible implementation manner of the seventh aspect, when sendingthe call message to the first UE, the transceiver is configured to senda second paging message to an MCPTT server of the first MCPTT user,where the second paging message is used to page the first UE to join themulti-group call, so that the MCPTT server of the first MCPTT user sendsa third paging message to the first UE, and the first UE joins themulti-group call according to the third paging message.

With reference to any one of the seventh aspect, or the first to theseventh possible implementation manners of the seventh aspect, in atenth possible implementation manner of the seventh aspect, when sendingthe call message to the first UE, the transceiver is configured to senda fourth paging message to an MCPTT server of an MCPTT group to whichthe first MCPTT user belongs, where the fourth paging message is used topage the first UE to join the multi-group call, so that the MCPTT serverof the MCPTT group to which the first MCPTT user belongs sends a fifthpaging message to the first UE or sends a fifth paging message to thefirst UE by using an MCPTT server of the first MCPTT user, and the firstUE joins the multi-group call according to the fifth paging message,where the fifth paging message is used to page the first UE to join themulti-group call.

With reference to any one of the seventh aspect, or the first to theseventh possible implementation manners of the seventh aspect, in aneleventh possible implementation manner of the seventh aspect, whensending the call message to the first UE, the transceiver is configuredto send a first notification message to the first UE, where the firstnotification message includes a session identifier of the multi-groupcall, and the first notification message is used to instruct the firstUE to join the multi-group call according to the session identifier, sothat the first UE joins the multi-group call according to the sessionidentifier.

With reference to any one of the seventh aspect, or the first to theseventh possible implementation manners of the seventh aspect, in atwelfth possible implementation manner of the seventh aspect, whensending the call message to the first UE, the transceiver is configuredto send a second notification message to an MCPTT server of the firstMCPTT user, where the second notification message includes a sessionidentifier of the multi-group call, and the second notification messageis used to instruct the first UE to join the multi-group call accordingto the session identifier, so that the MCPTT server of the first MCPTTuser sends a third notification message to the first UE, where the thirdnotification message includes the session identifier, and the thirdnotification message is used to instruct the first UE to join themulti-group call according to the session identifier, so that the firstUE joins the multi-group call according to the session identifier.

With reference to any one of the seventh aspect, or the first to theseventh possible implementation manners of the seventh aspect, in athirteenth possible implementation manner of the seventh aspect, whensending the call message to the first UE, the transceiver is configuredto send a fourth notification message to an MCPTT server of an MCPTTgroup to which the first MCPTT user belongs, where the fourthnotification message includes a session identifier of the multi-groupcall, and the fourth notification message is used to instruct the firstUE to join the multi-group call according to the session identifier, sothat the MCPTT server of the MCPTT group to which the first MCPTT userbelongs sends a fifth notification message to the first UE or sends afifth notification message to the first UE by using an MCPTT server ofthe first MCPTT user, and the first UE joins the multi-group callaccording to the session identifier.

According to an eighth aspect, an embodiment of the present inventionprovides UE, serving as first UE and including a transceiver, configuredto receive a call message, where the call message is used to add thefirst UE to a multi-group call involving N MCPTT groups, N is an integergreater than or equal to 2, a first MCPTT user is an associated user ofthe first UE, and the first MCPTT user is any MCPTT user in the N MCPTTgroups, and a processor, configured to join the multi-group callaccording to the call message.

With reference to the eighth aspect, in a first possible implementationmanner of the eighth aspect, when receiving the call message, thetransceiver is configured to receive a notification message, where thenotification message includes a session identifier of the multi-groupcall, and the notification message is used to instruct the first UE tojoin the multi-group call according to the session identifier, and whenjoining the multi-group call according to the call message, theprocessor is configured to join the multi-group call according to thesession identifier.

With reference to the eighth aspect or the first possible implementationmanner of the eighth aspect, in a second possible implementation mannerof the eighth aspect, the multi-group call involving the N MCPTT groupsis initiated by a second MCPTT user, and the first MCPTT user is anyMCPTT user in the N MCPTT groups except the second MCPTT user.

With reference to the eighth aspect, the first possible implementationmanner of the eighth aspect, or the second possible implementationmanner of the eighth aspect, in a third possible implementation mannerof the eighth aspect, when receiving the call message, the transceiveris configured to receive the call message that is sent by an MCPTTserver of an MCPTT group to which the first MCPTT user belongs, orreceive the call message that is sent by an MCPTT server of the firstMCPTT user, or receive the call message that is sent by an MCPTT serverof a temporary group that includes the N MCPTT groups.

With reference to the second possible implementation manner of theeighth aspect, in a fourth possible implementation manner of the eighthaspect, when receiving the call message, the transceiver is configuredto receive the call message that is sent by an MCPTT server of thesecond MCPTT user.

According to a ninth aspect, an embodiment of the present inventionprovides UE, serving as second UE and including a processor, configuredto generate a multi-group call setup message, where the multi-group callsetup message is used by a second MCPTT user to request a first MCPTTserver to set up a multi-group call involving N MCPTT groups, N is aninteger greater than or equal to 2, the second MCPTT user is anassociated user of the second UE, and an MCPTT group to which the secondMCPTT user belongs is at least one of the N MCPTT groups, and atransceiver, configured to send the multi-group call setup message tothe first MCPTT server.

With reference to the ninth aspect, in a first possible implementationmanner of the ninth aspect, the multi-group call setup message includesan identifier of a temporary group that includes the N MCPTT groups, andthe first MCPTT server is an MCPTT server of the temporary group.

With reference to the first possible implementation manner of the ninthaspect, in a second possible implementation manner of the ninth aspect,when sending the multi-group call setup message to the first MCPTTserver, the transceiver is configured to send the multi-group call setupmessage to the first MCPTT server by using an MCPTT server of the secondMCPTT user.

With reference to the first possible implementation manner of the ninthaspect or the second possible implementation manner of the ninth aspect,in a third possible implementation manner of the ninth aspect, theprocessor is further configured to create the temporary group before thetransceiver sends the multi-group call setup message to the first MCPTTserver.

With reference to the ninth aspect, in a fourth possible implementationmanner of the ninth aspect, the multi-group call setup message includesidentifiers of the N MCPTT groups, and the first MCPTT server is anMCPTT server of the second MCPTT user.

According to the multi-group call setup method and device provided inthe embodiments of the present invention, a first MCPTT serverdetermines to set up a multi-group call involving N MCPTT groups, andsends a call message to first UE, so that the first UE joins themulti-group call according to the call message, where a first MCPTT useris an associated user of the first UE, and the first MCPTT user is anyMCPTT user in the N MCPTT groups. In this way, the multi-group call canbe performed among the N MCPTT groups.

BRIEF DESCRIPTION OF THE DRAWINGS

To describe the technical solutions in the embodiments of the presentinvention more clearly, the following briefly describes the accompanyingdrawings required for describing the embodiments or the prior art.Apparently, the accompanying drawings in the following description showsome embodiments of the present invention, and persons of ordinary skillin the art may still derive other drawings from these accompanyingdrawings without creative efforts.

FIG. 1 is a flowchart of a first embodiment of a multi-group call setupmethod according to the some embodiments;

FIG. 2 is a flowchart of a second embodiment of a multi-group call setupmethod according to the some embodiments;

FIG. 3 is a flowchart of a third embodiment of a multi-group call setupmethod according to the some embodiments;

FIG. 4 is a flowchart of a fourth embodiment of a multi-group call setupmethod according to the some embodiments;

FIG. 5 is a flowchart of a fifth embodiment of a multi-group call setupmethod according to the some embodiments;

FIG. 6 is a flowchart of a sixth embodiment of a multi-group call setupmethod according to the some embodiments;

FIG. 7 is a schematic structural diagram of a first embodiment of anMCPTT server according to the some embodiments;

FIG. 8 is a schematic structural diagram of a first embodiment of UEaccording to the some embodiments;

FIG. 9 is a schematic structural diagram of a second embodiment of UEaccording to the some embodiments;

FIG. 10 is a schematic structural diagram of a second embodiment of anMCPTT server according to the some embodiments;

FIG. 11 is a schematic structural diagram of a third embodiment of UEaccording to the some embodiments; and

FIG. 12 is a schematic structural diagram of a fourth embodiment of UEaccording to the some embodiments.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

To make the objectives, technical solutions, and advantages of theembodiments of the present invention clearer, the following clearlydescribes the technical solutions in the embodiments of the presentinvention with reference to the accompanying drawings in the embodimentsof the present invention. Apparently, the described embodiments are somebut not all of the embodiments of the present invention. All otherembodiments obtained by persons of ordinary skill in the art based onthe embodiments of the present invention without creative efforts shallfall within the protection scope of the present invention.

FIG. 1 is a flowchart of a first embodiment of a multi-group call setupmethod according to the present invention. As shown in FIG. 1, themethod in this embodiment may include the following steps:

S101. A first MCPTT server determines to set up a multi-group callinvolving N MCPTT groups, where N is an integer greater than or equal to2.

S102. The first MCPTT server sends a call message to first UE, where thecall message is used to add the first UE to the multi-group call.

In this embodiment, the first MCPTT server may determine to set up themulti-group call involving the N MCPTT groups. The first MCPTT servermay determine, according to a preset policy, to set up the multi-groupcall involving the N MCPTT groups; or the first MCPTT server determines,according to timing of a timer, to set up the multi-group call involvingthe N MCPTT groups; or the first MCPTT server may determine, in a mannerdescribed in a second method embodiment of the present invention, to setup the multi-group call involving the N MCPTT groups. This embodiment ofthe present invention imposes no limitation on how the first MCPTTserver determines to set up the multi-group call involving the N MCPTTgroups.

Then, the first MCPTT server sends the call message to the first UE,where the call message is used to add the first UE to the multi-groupcall. An associated user of the first UE is referred to as a first MCPTTuser, and the associated user of the first UE refers to an MCPTT userwho uses the first UE. The first MCPTT user may be any MCPTT user in theN MCPTT groups. In this manner, the first MCPTT server may add UE usedby any MCPTT user in the N MCPTT groups to the multi-group call, and inthis way, the multi-group call can be performed among the N MCPTTgroups.

An optional implementation solution of S102 is similar to animplementation manner in which the first MCPTT server adds the first UEto the multi-group call in a fourth method embodiment of the presentinvention. For details, refer to the following descriptions. Details arenot described herein.

According to the multi-group call setup method provided in thisembodiment, a first MCPTT server determines to set up a multi-group callinvolving N MCPTT groups, and sends a call message to first UE, so thatthe first UE joins the multi-group call according to the call message,where a first MCPTT user is an associated user of the first UE, and thefirst MCPTT user is any MCPTT user in the N MCPTT groups. In this way,the multi-group call can be performed among the N MCPTT groups.

FIG. 2 is a flowchart of a second embodiment of a multi-group call setupmethod according to the present invention. As shown in FIG. 2, themethod in this embodiment may include the following steps.

S201. A first MCPTT server receives a multi-group call setup messagesent by second UE, where the multi-group call setup message is used by asecond MCPTT user to request the first MCPTT server to set up amulti-group call involving N MCPTT groups.

S202. The first MCPTT server determines, according to the multi-groupcall setup message, to set up the multi-group call.

In this embodiment, the second MCPTT user is a user who initiates themulti-group call involving the N MCPTT groups. Because the second MCPTTuser may belong to at least one MCPTT group, an MCPTT group to which thesecond MCPTT user belongs is at least one of the N MCPTT groups, thatis, the N MCPTT groups include the second MCPTT user. The second MCPTTuser is an associated user of the second UE, that is, the second UE isUE used by the second MCPTT user.

The first MCPTT server receives the multi-group call setup message sentby the second UE, where the multi-group call setup message is used bythe second MCPTT user to request the first MCPTT server to set up themulti-group call involving the N MCPTT groups. The first MCPTT serverdetermines, according to the multi-group call setup message, to set upthe multi-group call. N is an integer greater than or equal to 2, andeach MCPTT group includes at least one MCPTT user.

Optionally, the multi-group call setup message includes an identifier ofa temporary group that includes the N MCPTT groups, and the multi-groupcall setup message is used by the second MCPTT user to request the firstMCPTT server to set up, according to the identifier of the temporarygroup, the multi-group call involving the N MCPTT groups that form thetemporary group corresponding to the identifier.

Optionally, the multi-group call setup message includes identifiers ofthe N MCPTT groups, and the multi-group call setup message is used bythe second MCPTT user to request the first MCPTT server to set up,according to the identifiers of the N MCPTT groups, the multi-group callinvolving the N MCPTT groups that are corresponding to the Nidentifiers.

S203. The first MCPTT server sends a call message to first UE.

In this embodiment, a first MCPTT user is any MCPTT user in the N MCPTTgroups except the second MCPTT user, and the first MCPTT user is anassociated user of the first UE. The first MCPTT server that receivesthe multi-group call setup message may send the call message to thefirst UE, to add the first UE to the multi-group call. A process inwhich UE used by another MCPTT user joins the multi-group call issimilar, and details are not described herein. In this way, themulti-group call can be performed among the N MCPTT groups.

For an optional implementation solution of S202, refer to relateddescriptions in a fourth method embodiment of the present invention.

According to the multi-group call setup method provided in thisembodiment, a first MCPTT server receives a multi-group call setupmessage sent by second UE, where the multi-group call setup message isused by a second MCPTT user to request the first MCPTT server to set upa multi-group call involving N MCPTT groups; and then, the first MCPTTserver sends a call message to first UE (where an associated user of thefirst UE is any MCPTT user in the N MCPTT groups except the first MCPTTuser), so that the first UE joins the multi-group call. In this way, themulti-group call can be performed among the N MCPTT groups.

FIG. 3 is a flowchart of a third embodiment of a multi-group call setupmethod according to the present invention. As shown in FIG. 3, themethod in this embodiment may include the following steps:

S301. Second UE generates a multi-group call setup message, where themulti-group call setup message is used by a second MCPTT user to requesta first MCPTT server to set up a multi-group call involving N MCPTTgroups.

In this embodiment, an associated user of the second UE is the secondMCPTT user, that is, the second UE is UE used by the second MCPTT user.When the second MCPTT user initiates the multi-group call involving theN MCPTT groups, the second UE may determine, according to a useroperation, that the second MCPTT user initiates the multi-group callinvolving the N MCPTT groups. The second UE may generate the multi-groupcall setup message, where the multi-group call setup message is used bythe second MCPTT user to request the first MCPTT server to set up themulti-group call involving the N MCPTT groups, N is an integer greaterthan or equal to 2, and each MCPTT group includes at least one MCPTTuser. Because the second MCPTT user may belong to at least one MCPTTgroup, an MCPTT group to which the second MCPTT user belongs is at leastone of the N MCPTT groups.

S302. The second UE sends the multi-group call setup message to thefirst MCPTT server.

In this embodiment, the second UE sends the multi-group call setupmessage to the first MCPTT server. After receiving the multi-group callsetup message, the first MCPTT server may send a call message to firstUE according to the multi-group call setup message (where an associateduser of the first UE is any MCPTT user in the N MCPTT groups except thesecond MCPTT user), so that the first UE joins the multi-group callinvolving the N MCPTT groups. In this way, the multi-group call can beperformed among the N MCPTT groups.

Optionally, the multi-group call setup message includes an identifier ofa temporary group that includes the N MCPTT groups, and the multi-groupcall setup message is used by the second MCPTT user to request the firstMCPTT server to set up, according to the identifier of the temporarygroup, the multi-group call involving the N MCPTT groups that form thetemporary group corresponding to the identifier.

Optionally, the first MCPTT server is a server of the temporary group.

Optionally, the second UE may send the multi-group call setup message tothe server of the temporary group by using an MCPTT server of the secondMCPTT user.

Optionally, the multi-group call setup message includes identifiers ofthe N MCPTT groups, and the multi-group call setup message is used bythe second MCPTT user to request the first MCPTT server to set up,according to the identifiers of the N MCPTT groups, the multi-group callinvolving the N MCPTT groups that are corresponding to the Nidentifiers.

According to the multi-group call setup method provided in thisembodiment of the present invention, second UE generates a multi-groupcall setup message, and sends the multi-group call setup message to afirst MCPTT server, where the multi-group call setup message is used bya second MCPTT user to request the first MCPTT server to set up amulti-group call involving N MCPTT groups, so that the first MCPTTserver can send a call message to first UE (where an associated user ofthe first UE is any MCPTT user in the N MCPTT groups except the secondMCPTT user), and the first UE joins the multi-group call. In this way,the multi-group call can be performed among the N MCPTT groups.

FIG. 4 is a flowchart of a fourth embodiment of a multi-group call setupmethod according to the present invention. As shown in FIG. 4, amulti-group call setup message in this embodiment includes an identifierof a temporary group that includes N MCPTT groups, and a first MCPTTserver is an MCPTT server of the temporary group. The method in thisembodiment may include the following steps:

S401. Second UE generates a multi-group call setup message.

In this embodiment, for a specific implementation process of S401, referto related descriptions in the third method embodiment of the presentinvention. Details are not described herein.

S402. The second UE sends the multi-group call setup message to an MCPTTserver of a temporary group.

In this embodiment, N MCPTT groups form a temporary group. For thetemporary group, there is an MCPTT server of the temporary group.Therefore, the second UE sends the multi-group call setup message to theMCPTT server of the temporary group.

In an optional implementation solution, the second UE may directly sendthe multi-group call setup message to the MCPTT server of the temporarygroup without using another network element device.

In another optional implementation solution, the second UE may send themulti-group call setup message to the MCPTT server of the temporarygroup by using another network device (for example, an MCPTT server of asecond MCPTT user), that is, the second UE sends the multi-group callsetup message to the MCPTT server of the second MCPTT user, and theserver of the second MCPTT user forwards the multi-group call setupmessage to the MCPTT server of the temporary group.

In this embodiment, the multi-group call setup message includes anidentifier of the temporary group that includes the N MCPTT groups.

Optionally, before performing S402, the second UE may further obtain theidentifier of the temporary group.

Optionally, before performing S402, the second UE may further create thetemporary group.

S403. The MCPTT server of the temporary group determines, according tothe multi-group call setup message, to set up a multi-group call.

S404. The MCPTT server of the temporary group obtains information aboutthe temporary group according to an identifier of the temporary group.

In this embodiment, after receiving the multi-group call setup message,the MCPTT server of the temporary group may determine to set up amulti-group call involving the N MCPTT groups that form the temporarygroup, and then obtain the information about the temporary groupaccording to the identifier of the temporary group in the multi-groupcall setup message.

The information about the temporary group includes the identifier of thetemporary group and identifiers of the N MCPTT groups.

Optionally, the information about the temporary group may furtherinclude information about an MCPTT user in at least one of the N MCPTTgroups.

Then, the MCPTT server of the temporary group may send a call message tofirst UE, to add the first UE to the multi-group call, where anassociated user of the first UE is a first MCPTT user, and the firstMCPTT user is any user in the N MCPTT groups except the second MCPTTuser.

A first feasible implementation manner in which the MCPTT server of thetemporary group sends the call message to the first UE includes S405.

S405. The MCPTT server of the temporary group sends a first pagingmessage to the first UE.

In this embodiment, the first paging message is used to page the firstUE to join the multi-group call, so that the first UE joins themulti-group call according to the first paging message.

In a first optional implementation solution, if the information aboutthe temporary group includes information about the first MCPTT user, theMCPTT server of the temporary group sends the first paging message tothe first UE according to the information about the first MCPTT user.The information about the first MCPTT user may include an identifier ofthe first MCPTT user and location information of the first MCPTT user.

In a second optional implementation solution, if the information aboutthe temporary group includes information about the first MCPTT user,when the information about the first MCPTT user includes an identifierof the first MCPTT user but does not include location information of thefirst MCPTT user, the MCPTT server of the temporary group obtains,according to the identifier of the first MCPTT user, the locationinformation of the first MCPTT user from an MCPTT server of the firstMCPTT user or a database that stores information about an MCPTT user,and then sends the first paging message to the first UE.

Optionally, the first paging message includes the identifier of thetemporary group.

Optionally, the first paging message further includes the identifier ofthe first MCPTT user.

A second feasible implementation manner in which the MCPTT server of thetemporary group sends the call message to the first UE includes S406 andS407.

S406. The MCPTT server of the temporary group sends a second pagingmessage to an MCPTT server of the first MCPTT user.

In this embodiment, the second paging message is used to page the firstUE to join the multi-group call, so that the MCPTT server of the firstMCPTT user sends a third paging message to the first UE, where the thirdpaging message is used to page the first UE to join the multi-groupcall, so that the first UE joins the multi-group call according to thethird paging message.

In an optional implementation solution, if the information about thetemporary group includes information about the first MCPTT user, whenthe information about the first MCPTT user includes an identifier of thefirst MCPTT user but does not include location information of the firstMCPTT user, and the MCPTT server of the temporary group is not the MCPTTserver of the first MCPTT user, the MCPTT server of the temporary groupsends the second paging message to the MCPTT server of the first MCPTTuser according to the identifier of the first MCPTT user and themulti-group call setup message.

Optionally, the second paging message includes the identifier of thetemporary group.

Optionally, the second paging message further includes the identifier ofthe first MCPTT user.

S407. The MCPTT server of the first MCPTT user sends a third pagingmessage to the first UE.

In this embodiment, the MCPTT server of the first MCPTT user receivesthe second paging message sent by the MCPTT server of the temporarygroup, and then sends the third paging message to the first UE, wherethe third paging message is used to page the first UE to join themulti-group call.

Optionally, the third paging message includes the identifier of thetemporary group.

Optionally, the third paging message further includes the identifier ofthe first MCPTT user.

It should be noted that the second paging message and the third pagingmessage may be a same message, that is, the MCPTT server of the firstMCPTT user forwards a message that is sent by the MCPTT server of thetemporary group; or the second paging message and the third pagingmessage may be different messages, that is, the MCPTT server of thefirst MCPTT user may parse a message that is sent by the MCPTT server ofthe temporary group, and then send a message obtained after parsingprocessing to the first UE.

A third feasible implementation manner in which the MCPTT server of thetemporary group sends the call message to the first UE includes S408 andS409.

S408. The MCPTT server of the temporary group sends a fourth pagingmessage to an MCPTT server of an MCPTT group to which the first MCPTTuser belongs.

In this embodiment, the fourth paging message is used to page the firstUE to join the multi-group call, so that the MCPTT server of the MCPTTgroup to which the first MCPTT user belongs sends a fifth paging messageto the first UE, and the first UE joins the multi-group call accordingto the fifth paging message.

In an optional implementation solution, when the information about thetemporary group does not include information about the first MCPTT user,the MCPTT server of the temporary group sends, according to anidentifier of the MCPTT group to which the first MCPTT user belongs, thefourth paging message to the MCPTT server of the MCPTT group to whichthe first MCPTT user belongs.

Optionally, the fourth paging message includes the identifiers of the NMCPTT groups.

Optionally, the fourth paging message further includes an identifier ofthe first MCPTT user.

S409. The MCPTT server of the MCPTT group to which the first MCPTT userbelongs sends a fifth paging message to the first UE.

In this embodiment, after receiving the fourth paging message, the MCPTTserver of the MCPTT group to which the first MCPTT user belongs may sendthe fifth paging message to the first UE. The MCPTT server of the MCPTTgroup to which the first MCPTT user belongs may directly send the fifthpaging message to the first UE without using another network elementdevice; or the MCPTT server of the MCPTT group to which the first MCPTTuser belongs may send the fifth paging message to the first UE by usinganother network element device (for example, an MCPTT server of thefirst MCPTT user).

Optionally, the fifth paging message that is sent to the first UE by theMCPTT server of the MCPTT group to which the first MCPTT user belongsmay carry the identifier of the first MCPTT user.

It should be noted that the fourth paging message and the fifth pagingmessage may be a same message, that is, an MCPTT server between theMCPTT server of the temporary group and the first UE only forwards amessage that is sent by the MCPTT server of the temporary group; or thefourth paging message and the fifth paging message may be differentmessages, that is, an MCPTT server between the MCPTT server of thetemporary group and the first UE may parse a message that is sent by theMCPTT server of the temporary group, and then send a message obtainedafter parsing processing.

S410. The first UE joins the multi-group call.

In this embodiment, the first UE joins the multi-group call according tothe received first paging message, or the received third paging message,or the received fifth paging message.

Optionally, the first UE may further send a paging response message toan MCPTT server that sends a paging message (for example, the firstpaging message, the second paging message, or the fifth paging message)to the first UE. The paging response message is used to indicate thatthe first UE agrees to join the multi-group call.

Optionally, if the first UE does not join the multi-group call, thefirst UE may also send a paging response message to an MCPTT server thatsends a paging message (for example, the first paging message, thesecond paging message, or the fifth paging message) to the first UE. Thepaging response message is used to indicate that the first UE refuses tojoin the multi-group call.

If the MCPTT server that receives the paging response message of thefirst UE is not the MCPTT server of the temporary group, the MCPTTserver sends a paging acknowledgement message to the MCPTT server of thetemporary group according to all received paging response messages. Thepaging acknowledgement message is used to indicate a multi-group callsetup result, for example, completion of setup or a failure of setup,and optionally, further indicate UE that is used by an MCPTT user andthat agrees to join the multi-group call, and an MCPTT user who refusesto join the multi-group call.

It should be noted that the MCPTT server of the temporary group may sendthe call message to the first UE with reference to at least one of theforegoing first, second, or third feasible implementation manner, sothat the first UE joins the multi-group call.

A fourth feasible implementation manner in which the MCPTT server of thetemporary group sends the call message to the first UE includes S411.

S411. The MCPTT server of the temporary group sends a first notificationmessage to the first UE.

In this embodiment, the first notification message includes a sessionidentifier of the multi-group call, and the first notification messageis used to instruct the first UE to join the multi-group call accordingto the session identifier, so that the first UE joins the multi-groupcall according to the session identifier.

In an optional implementation solution, if the information about thetemporary group includes information about the first MCPTT user, theMCPTT server of the temporary group sends the first notification messageto the first UE according to the information about the first MCPTT user.The information about the first MCPTT user may include an identifier ofthe first MCPTT user and location information of the first MCPTT user.

In another optional implementation solution, if the information aboutthe temporary group includes information about the first MCPTT user,when the information about the first MCPTT user includes an identifierof the first MCPTT user but does not include location information of thefirst MCPTT user, the MCPTT server of the temporary group obtains,according to the identifier of the first MCPTT user, the locationinformation of the first MCPTT user from an MCPTT server of the firstMCPTT user or a database that stores information about an MCPTT user,and then sends the first notification message to the first UE.

Optionally, the first notification message includes the identifier ofthe temporary group.

Optionally, the first notification message includes the identifier ofthe first MCPTT user.

A fifth feasible implementation manner in which the MCPTT server of thetemporary group sends the call message to the first UE includes S412 andS413.

S412. The MCPTT server of the temporary group sends a secondnotification message to an MCPTT server of the first MCPTT user.

In this embodiment, the second notification message includes a sessionidentifier of the multi-group call, and the second notification messageis used to instruct the first UE to join the multi-group call accordingto the session identifier, so that the MCPTT server of the first MCPTTuser sends a third notification message to the first UE, where the thirdnotification message includes the session identifier of the multi-groupcall, and the third notification message is used to instruct the firstUE to join the multi-group call according to the session identifier, sothat the first UE joins the multi-group call according to the sessionidentifier in the third notification message.

In an optional implementation solution, if the information about thetemporary group includes information about the first MCPTT user, whenthe information about the first MCPTT user includes an identifier of thefirst MCPTT user but does not include location information of the firstMCPTT user, and the MCPTT server of the temporary group is not the MCPTTserver of the first MCPTT user, the MCPTT server of the temporary groupsends the second notification message to the MCPTT server of the firstMCPTT user according to the identifier of the first MCPTT user.

Optionally, the second notification message includes the identifier ofthe temporary group.

Optionally, the second notification message further includes theidentifier of the first MCPTT user.

S413. The MCPTT server of the first MCPTT user sends a thirdnotification message to the first UE.

In this embodiment, the MCPTT server of the first MCPTT user receivesthe second notification message sent by the MCPTT server of thetemporary group, and then sends the third notification message to thefirst UE, where the third notification message includes the sessionidentifier of the multi-group call, and the third notification messageis used to instruct the first UE to join the multi-group call accordingto the session identifier.

Optionally, the third notification message includes the identifier ofthe temporary group. Optionally, the third notification message furtherincludes the identifier of the first MCPTT user.

It should be noted that the second notification message and the thirdnotification message may be a same message, that is, the MCPTT server ofthe first MCPTT user forwards a message that is sent by the MCPTT serverof the temporary group; or the second notification message and the thirdnotification message may be different messages, that is, the MCPTTserver of the first MCPTT user may parse a message that is sent by theMCPTT server of the temporary group, and then send a message obtainedafter parsing processing to the first UE.

A sixth feasible implementation manner in which the MCPTT server of thetemporary group sends the call message to the first UE includes S414 andS415.

S414. The MCPTT server of the temporary group sends a fourthnotification message to an MCPTT server of an MCPTT group to which thefirst MCPTT user belongs.

In this embodiment, the fourth notification message includes a sessionidentifier of the multi-group call, and the fourth notification messageis used to instruct the first UE to join the multi-group call accordingto the session identifier, so that the MCPTT server of the MCPTT groupto which the first MCPTT user belongs sends a fifth notification messageto the first UE, and the first UE joins the multi-group call accordingto the session identifier in the fifth notification message.

In an optional implementation solution, when the information about thetemporary group does not include information about the first MCPTT user,the MCPTT server of the temporary group sends, according to anidentifier of the MCPTT group to which the first MCPTT user belongs, thefourth notification message to the MCPTT server of the MCPTT group towhich the first MCPTT user belongs.

Optionally, before sending the foregoing first notification message, theforegoing second notification message, or the foregoing fourthnotification message, the MCPTT server of the temporary group mayfurther obtain the session identifier of the multi-group call.

S415. The MCPTT server of the MCPTT group to which the first MCPTT userbelongs sends a fifth notification message to the first UE.

In this embodiment, after receiving the fourth notification message, theMCPTT server of the MCPTT group to which the first MCPTT user belongsmay send the fifth notification message to the first UE. The MCPTTserver of the MCPTT group to which the first MCPTT user belongs maydirectly send the fifth notification message to the first UE withoutusing another network element device; or the MCPTT server of the MCPTTgroup to which the first MCPTT user belongs may send the fifthnotification message to the first UE by using another network elementdevice (for example, an MCPTT server of the first MCPTT user).

Optionally, the fifth notification message that is sent to the first UEby the MCPTT server of the MCPTT group to which the first MCPTT userbelongs may carry an identifier of the first MCPTT user.

It should be noted that the fourth notification message and the fifthnotification message may be a same message, that is, an MCPTT serverbetween the MCPTT server of the temporary group and the first UE onlyforwards a message that is sent by the MCPTT server of the temporarygroup; or the fourth notification message and the fifth notificationmessage may be different messages, that is, an MCPTT server between theMCPTT server of the temporary group and the first UE may parse a messagethat is sent by the MCPTT server of the temporary group, and then send amessage obtained after parsing processing.

S416. The first UE joins the multi-group call according to a sessionidentifier.

In this embodiment, when the first UE determines to join the multi-groupcall, the first UE joins the multi-group call according to the sessionidentifier in the received notification message (the first notificationmessage, or the third notification message, or the fifth notificationmessage). If the first UE determines not to join the multi-group call,the first UE ignores the notification message and does not join themulti-group call.

It should be noted that after receiving the foregoing notificationmessage (the first notification message, or the third notificationmessage, or the fifth notification message), the first UE mayimmediately join the multi-group call according to the sessionidentifier; or when receiving the foregoing notification message (thefirst notification message, or the third notification message, or thefifth notification message), the first UE may not immediately join themulti-group call. Due to a session collision or for another reason, thefirst UE may join the multi-group call according to the sessionidentifier after a delay of a period of time.

According to the multi-group call setup method provided in thisembodiment, second UE sends a multi-group call setup message to an MCPTTserver of a temporary group, where the multi-group call setup message isused by a second MCPTT user to request the MCPTT server of the temporarygroup to set up a multi-group call involving N MCPTT groups; and then,the MCPTT server of the temporary group obtains information about thetemporary group according to an identifier of the temporary group, andthen adds first UE to the multi-group call (where an associated user ofthe first UE is any MCPTT user in the N MCPTT groups except the secondMCPTT user). In this way, the multi-group call can be performed amongthe N MCPTT groups.

FIG. 5 is a flowchart of a fifth embodiment of a multi-group call setupmethod according to the present invention. As shown in FIG. 5, amulti-group call setup message in this embodiment includes identifiersof N MCPTT groups, and a first MCPTT server is an MCPTT server of asecond MCPTT user. The method in this embodiment may include thefollowing steps:

S501. Second UE generates a multi-group call setup message.

In this embodiment, for a specific implementation process of S501, referto related descriptions in the fourth method embodiment of the presentinvention. Details are not described herein.

S502. The second UE sends the multi-group call setup message to an MCPTTserver of the second MCPTT user.

S503. The MCPTT server of the second MCPTT user determines, according tothe multi-group call setup message, to set up a multi-group call.

In this embodiment, the multi-group call setup message includesidentifiers of N MCPTT groups. Optionally, the MCPTT server of thesecond MCPTT user may obtain information about an MCPTT user in at leastone of the N MCPTT groups according to the identifiers of the N MCPTTgroups.

After the MCPTT server of the second MCPTT user receives the multi-groupcall setup message, the MCPTT server of the second MCPTT user may send acall message to first UE, to add the first UE to the multi-group call,where a first MCPTT user is any user in the N MCPTT groups except thesecond MCPTT user.

A first feasible implementation manner in which the MCPTT server of thesecond MCPTT user sends the call message to the first UE includes S504.

S504. The MCPTT server of the second MCPTT user sends a first pagingmessage to the first UE.

In this embodiment, the first paging message is used to page the firstUE to join the multi-group call, so that the first UE joins themulti-group call according to the first paging message.

In a first optional implementation solution, if the MCPTT server of thesecond MCPTT user may obtain information about the first MCPTT user, theMCPTT server of the second MCPTT user sends the first paging message tothe first UE according to the information about the first MCPTT user.The information about the first MCPTT user may include an identifier ofthe first MCPTT user and location information of the first MCPTT user.

In a second optional implementation solution, if the MCPTT server of thesecond MCPTT user may obtain information about the first MCPTT user,when the information about the first MCPTT user includes an identifierof the first MCPTT user but does not include location information of thefirst MCPTT user, the MCPTT server of the second MCPTT user obtains,according to the identifier of the first MCPTT user, the locationinformation of the first MCPTT user from an MCPTT server of the firstMCPTT user or a database that stores information about an MCPTT user,and then sends the first paging message to the first UE.

Optionally, the first paging message includes the identifiers of the NMCPTT groups.

Optionally, the first paging message further includes the identifier ofthe first MCPTT user.

A second feasible implementation manner in which the MCPTT server of thesecond MCPTT user sends the call message to the first UE includes S505and S506.

S505. The MCPTT server of the second MCPTT user sends a second pagingmessage to an MCPTT server of the first MCPTT user.

In this embodiment, the second paging message is used to page the firstUE to join the multi-group call, so that the MCPTT server of the firstMCPTT user sends a third paging message to the first UE, where the thirdpaging message is used to page the first UE to join the multi-groupcall, so that the first UE joins the multi-group call according to thethird paging message.

In an optional implementation solution, if the MCPTT server of thesecond MCPTT user may obtain information about the first MCPTT user,when the information about the first MCPTT user includes an identifierof the first MCPTT user but does not include location information of thefirst MCPTT user, and the MCPTT server of the second MCPTT user is notthe MCPTT server of the first MCPTT user, the MCPTT server of the secondMCPTT user sends the second paging message to the MCPTT server of thefirst MCPTT user according to the identifier of the first MCPTT user.

Optionally, the second paging message includes the identifiers of the NMCPTT groups.

Optionally, the second paging message further includes the identifier ofthe first MCPTT user.

S506. The MCPTT server of the first MCPTT user sends a third pagingmessage to the first UE.

In this embodiment, the MCPTT server of the first MCPTT user receivesthe second paging message sent by the MCPTT server of the second MCPTTuser, and then sends the third paging message to the first UE, where thethird paging message is used to page the first UE to join themulti-group call.

Optionally, the third paging message includes the identifiers of the NMCPTT groups.

Optionally, the third paging message further includes the identifier ofthe first MCPTT user.

It should be noted that the second paging message and the third pagingmessage may be a same message, that is, the MCPTT server of the firstMCPTT user forwards a message that is sent by the MCPTT server of thesecond MCPTT user; or the second paging message and the third pagingmessage may be different messages, that is, the MCPTT server of thefirst MCPTT user may parse a message that is sent by the MCPTT server ofthe second MCPTT user, and then send a message obtained after parsingprocessing to the first UE.

A third feasible implementation manner in which the MCPTT server of thesecond MCPTT user sends the call message to the first UE includes S507and S508.

S507. The MCPTT server of the second MCPTT user sends a fourth pagingmessage to an MCPTT server of an MCPTT group to which the first MCPTTuser belongs.

In this embodiment, the fourth paging message is used to page the firstUE to join the multi-group call, so that the MCPTT server of the MCPTTgroup to which the first MCPTT user belongs sends a fifth paging messageto the first UE, and the first UE joins the multi-group call accordingto the fifth paging message.

In an optional implementation solution, when the MCPTT server of thesecond MCPTT user does not obtain information about the first MCPTTuser, the MCPTT server of the second MCPTT user sends, according to anidentifier of the MCPTT group to which the first MCPTT user belongs, thefourth paging message to the MCPTT server of the MCPTT group to whichthe first MCPTT user belongs.

Optionally, the fourth paging message includes the identifiers of the NMCPTT groups.

Optionally, the fourth paging message further includes an identifier ofthe first MCPTT user.

S508. The MCPTT server of the MCPTT group to which the first MCPTT userbelongs sends a fifth paging message to the first UE.

In this embodiment, after receiving the fourth paging message, the MCPTTserver of the MCPTT group to which the first MCPTT user belongs may sendthe fifth paging message to the first UE. The MCPTT server of the MCPTTgroup to which the first MCPTT user belongs may directly send the fifthpaging message to the first UE without using another network elementdevice; or the MCPTT server of the MCPTT group to which the first MCPTTuser belongs may send the fifth paging message to the first UE by usinganother network element device (for example, an MCPTT server of thefirst MCPTT user).

Optionally, the fifth paging message that is sent to the first UE by theMCPTT server of the MCPTT group to which the first MCPTT user belongsmay carry the identifier of the first MCPTT user.

It should be noted that the fourth paging message and the fifth pagingmessage may be a same message, that is, an MCPTT server between theMCPTT server of the second MCPTT user and the first UE only forwards amessage that is sent by the MCPTT server of the second MCPTT user; orthe fourth paging message and the fifth paging message may be differentmessages, that is, an MCPTT server between the MCPTT server of thesecond MCPTT user and the first UE may parse a message that is sent bythe MCPTT server of the second MCPTT user, and then send a messageobtained after parsing processing.

S509. The first UE joins the multi-group call.

In this embodiment, the first UE joins the multi-group call according tothe received first paging message, or the received third paging message,or the received fifth paging message.

Optionally, the first UE may further send a paging response message toan MCPTT server that sends a paging message (for example, the firstpaging message, the second paging message, or the fifth paging message)to the first UE. The paging response message is used to indicate thatthe first UE agrees to join the multi-group call.

Optionally, if the first UE does not join the multi-group call, thefirst UE may also send a paging response message to an MCPTT server thatsends a paging message (for example, the first paging message, thesecond paging message, or the fifth paging message) to the first UE. Thepaging response message is used to indicate that the first UE refuses tojoin the multi-group call.

If the MCPTT server that receives the paging response message of thefirst UE is not the MCPTT server of the second MCPTT user, the MCPTTserver sends a paging acknowledgement message to the MCPTT server of thesecond MCPTT user according to all received paging response messages.The paging acknowledgement message is used to indicate UE that is usedby an MCPTT user and that agrees to join the multi-group call, and anMCPTT user who refuses to join the multi-group call.

It should be noted that the MCPTT server of the second MCPTT user mayadd, with reference to at least one of the foregoing first, second, orthird feasible implementation manner, UE used by an MCPTT user in the NMCPTT groups to the multi-group call.

A fourth feasible implementation manner in which the MCPTT server of thesecond MCPTT user sends the call message to the first UE includes S510.

S510. The MCPTT server of the second MCPTT user sends a firstnotification message to the first UE.

In this embodiment, the first notification message includes a sessionidentifier of the multi-group call, and the first notification messageis used to instruct the first UE to join the multi-group call accordingto the session identifier, so that the first UE joins the multi-groupcall according to the session identifier.

In an optional implementation solution, if the MCPTT server of thesecond MCPTT user may obtain information about the first MCPTT user, theMCPTT server of the second MCPTT user sends the first notificationmessage to the first UE according to the information about the firstMCPTT user. The information about the first MCPTT user may include anidentifier of the first MCPTT user and location information of the firstMCPTT user.

In another optional implementation solution, if the MCPTT server of thesecond MCPTT user may obtain information about the first MCPTT user,when the information about the first MCPTT user includes an identifierof the first MCPTT user but does not include location information of thefirst MCPTT user, the MCPTT server of the second MCPTT user obtains,according to the identifier of the first MCPTT user, the locationinformation of the first MCPTT user from an MCPTT server of the firstMCPTT user or a database that stores information about an MCPTT user,and then sends the first notification message to the first UE.

Optionally, the first notification message includes the identifiers ofthe N MCPTT groups.

Optionally, the first notification message includes the identifier ofthe first MCPTT user.

A fifth feasible implementation manner in which the MCPTT server of thesecond MCPTT user sends the call message to the first UE includes S511and S512.

S511. The MCPTT server of the second MCPTT user sends a secondnotification message to an MCPTT server of the first MCPTT user.

In this embodiment, the second notification message includes a sessionidentifier of the multi-group call, and the second notification messageis used to instruct the first UE to join the multi-group call accordingto the session identifier, so that the MCPTT server of the first MCPTTuser sends a third notification message to the first UE, where the thirdnotification message includes the session identifier of the multi-groupcall, and the third notification message is used to instruct the firstUE to join the multi-group call according to the session identifier, sothat the first UE joins the multi-group call according to the sessionidentifier in the third notification message.

In an optional implementation solution, if the MCPTT server of thesecond MCPTT user may obtain information about the first MCPTT user,when the information about the first MCPTT user includes an identifierof the first MCPTT user but does not include location information of thefirst MCPTT user, the MCPTT server of the second MCPTT user sends thesecond notification message to the MCPTT server of the first MCPTT useraccording to the identifier of the first MCPTT user.

Optionally, the second notification message includes the identifiers ofthe N MCPTT groups.

Optionally, the second notification message further includes theidentifier of the first MCPTT user.

S512. The MCPTT server of the first MCPTT user sends a thirdnotification message to the first UE.

In this embodiment, the MCPTT server of the first MCPTT user receivesthe second notification message sent by the MCPTT server of the secondMCPTT user, and then sends the third notification message to the firstUE, where the third notification message includes the session identifierof the multi-group call, and the third notification message is used toinstruct the first UE to join the multi-group call according to thesession identifier.

Optionally, the third notification message includes the identifiers ofthe N MCPTT groups.

Optionally, the third notification message further includes theidentifier of the first MCPTT user.

It should be noted that the second notification message and the thirdnotification paging message may be a same message, that is, the MCPTTserver of the first MCPTT user forwards a message that is sent by theMCPTT server of the second MCPTT user; or the second notificationmessage and the third notification message may be different messages,that is, the MCPTT server of the first MCPTT user may parse a messagethat is sent by the MCPTT server of the second MCPTT user, and then senda message obtained after parsing processing to the first UE.

A sixth feasible implementation manner in which the MCPTT server of thesecond MCPTT user sends the call message to the first UE includes S513and S514.

S513. The MCPTT server of the second MCPTT user sends a fourthnotification message to an MCPTT server of an MCPTT group to which thefirst MCPTT user belongs.

In this embodiment, the fourth notification message includes a sessionidentifier of the multi-group call, and the fourth notification messageis used to instruct the first UE to join the multi-group call accordingto the session identifier, so that the MCPTT server of the MCPTT groupto which the first MCPTT user belongs sends a fifth notification messageto the first UE, and the first UE joins the multi-group call accordingto the session identifier in the fifth notification message.

In an optional implementation solution, when the MCPTT server of thesecond MCPTT user does not obtain information about the first MCPTTuser, the MCPTT server of the second MCPTT user sends, according to anidentifier of the MCPTT group to which the first MCPTT user belongs, thefourth notification message to the MCPTT server of the MCPTT group towhich the first MCPTT user belongs.

Optionally, before sending the foregoing first notification message, theforegoing second notification message, or the foregoing fourthnotification message, the MCPTT server of the second MCPTT user mayfurther obtain the session identifier of the multi-group call.

S514. The MCPTT server of the MCPTT group to which the first MCPTT userbelongs sends a fifth notification message to the first UE.

In this embodiment, after receiving the fourth notification message, theMCPTT server of the MCPTT group to which the first MCPTT user belongsmay send the fifth notification message to the first UE. The MCPTTserver of the MCPTT group to which the first MCPTT user belongs maydirectly send the fifth notification message to the first UE withoutusing another network element device; or the MCPTT server of the MCPTTgroup to which the first MCPTT user belongs may send the fifthnotification message to the first UE by using another network elementdevice (for example, an MCPTT server of the first MCPTT user).

Optionally, the fifth notification message that is sent to the first UEby the MCPTT server of the MCPTT group to which the first MCPTT userbelongs may carry an identifier of the first MCPTT user.

It should be noted that the fourth notification message and the fifthnotification message may be a same message, that is, an MCPTT serverbetween the MCPTT server of the second MCPTT user and the first UE onlyforwards a message that is sent by the MCPTT server of the second MCPTTuser; or the fourth notification message and the fifth notificationmessage may be different messages, that is, an MCPTT server between theMCPTT server of the second MCPTT user and the first UE may parse amessage that is sent by the MCPTT server of the second MCPTT user, andthen send a message obtained after parsing processing.

S515. The first UE joins the multi-group call according to a sessionidentifier.

In this embodiment, when the first UE determines to join the multi-groupcall, the first UE joins the multi-group call according to the sessionidentifier in the received notification message (the first notificationmessage, or the third notification message, or the fifth notificationmessage).

If the first UE determines not to join the multi-group call, the firstUE ignores the notification message and does not join the multi-groupcall.

It should be noted that after receiving the foregoing notificationmessage (the first notification message, or the third notificationmessage, or the fifth notification message), the first UE mayimmediately join the multi-group call according to the sessionidentifier; or when receiving the foregoing notification message (thefirst notification message, or the third notification message, or thefifth notification message), the first UE may not immediately join themulti-group call. Due to a session collision or for another reason, thefirst UE may join the multi-group call according to the sessionidentifier after a delay of a period of time.

According to the multi-group call setup method provided in thisembodiment, second UE sends a multi-group call setup message to an MCPTTserver of a second MCPTT user, and the MCPTT server of the second MCPTTuser adds first UE to a multi-group call (where an associated user ofthe first UE is any MCPTT user in N MCPTT groups except the second MCPTTuser). In this way, the multi-group call can be performed among the NMCPTT groups.

FIG. 6 is a flowchart of a sixth embodiment of a multi-group call setupmethod according to the present invention. As shown in FIG. 6, themethod in this embodiment may include the following steps:

S601. First UE receives a call message, where the call message is usedto add the first UE to a multi-group call involving N MCPTT groups.

In this embodiment, N is an integer greater than or equal to 2. EachMCPTT group includes at least one MCPTT user. An associated user of thefirst UE is a first MCPTT user, that is, UE used by the first MCPTT useris the first UE. The first MCPTT user is any MCPTT user in the N MCPTTgroups, and an MCPTT group to which the first MCPTT user belongs is atleast one of the N MCPTT groups.

S602. The first UE joins the multi-group call according to the callmessage.

Optionally, the receiving, by first UE, a call message includesreceiving, by the first UE, a notification message, where thenotification message includes a session identifier of the multi-groupcall involving the N MCPTT groups, and the notification message is usedto instruct the first UE to join the multi-group call according to thesession identifier.

The joining, by the first UE, the multi-group call according to the callmessage includes joining, by the first UE, the multi-group callaccording to the session identifier.

Optionally, the multi-group call involving the N MCPTT groups isinitiated by a second MCPTT user, and the first MCPTT user who uses thefirst UE is any MCPTT user in the N MCPTT groups except the second MCPTTuser.

Optionally, the receiving, by first UE, a call message includesreceiving, by the first UE, the call message that is sent by an MCPTTserver of an MCPTT group to which the first MCPTT user belongs; orreceiving, by the first UE, the call message that is sent by an MCPTTserver of the first MCPTT user; or receiving, by the first UE, the callmessage that is sent by an MCPTT server of a temporary group thatincludes the N MCPTT groups.

Optionally, the call message further includes an identifier of thetemporary group that includes the N MCPTT groups.

Optionally, the receiving, by first UE, a call message includesreceiving, by the first UE, the call message that is sent by an MCPTTserver of an MCPTT group to which the first MCPTT user belongs; orreceiving, by the first UE, the call message that is sent by an MCPTTserver of the first MCPTT user; or receiving, by the first UE, the callmessage that is sent by an MCPTT server of the second MCPTT user.

Optionally, the call message further includes identifiers of the N MCPTTgroups.

Optionally, after performing S601, the first UE performs, instead ofS602, when the first UE does not need to join the multi-group call,ignoring, by the first UE, the call message.

For a specific implementation process of this embodiment, refer torelated descriptions in the foregoing method embodiments of the presentinvention. Details are not described herein.

According to the multi-group call setup method provided in thisembodiment, first UE receives a call message, where the call message isused to add the first UE to a multi-group call involving N MCPTT groups;and then joins the multi-group call according to the call message. Inthis way, the multi-group call can be performed among the N MCPTTgroups.

It should be noted that the foregoing described steps performed by theUE are triggered by the UE according to a user operation for performing,and the UE physically performs the foregoing steps.

It should be noted that, if the foregoing MCPTT servers that performinteraction belong to different MCPTT systems, interaction between theMCPTT servers may further need to be performed by using an intermediatenetwork element entity, for example, an interworking gateway(interworking Gateway).

FIG. 7 is a schematic structural diagram of a first embodiment of anMCPTT server according to the present invention. As shown in FIG. 7, theMCPTT server in this embodiment serves as a first MCPTT server and mayinclude a processing unit 11 and a transceiver unit 12.

The processing unit 11 is configured to determine to set up amulti-group call involving N MCPTT groups, where N is an integer greaterthan or equal to 2.

The transceiver unit 12 is configured to send a call message to firstUE, where the call message is used to add the first UE to themulti-group call.

A first MCPTT user is an associated user of the first UE, and the firstMCPTT user is any MCPTT user in the N MCPTT groups.

Optionally, before the processing unit 11 determines to set up themulti-group call involving the N MCPTT groups, the transceiver unit 12is further configured to receive a multi-group call setup message sentby second UE, where the multi-group call setup message is used by asecond MCPTT user to request the first MCPTT server to set up themulti-group call involving the N MCPTT groups.

The second MCPTT user is an associated user of the second UE, and anMCPTT group to which the second MCPTT user belongs is at least one ofthe N MCPTT groups.

When determining to set up the multi-group call involving the N MCPTTgroups, the processing unit 11 is configured to determine, according tothe multi-group call setup message, to set up the multi-group call.

The first MCPTT user is any MCPTT user in the N MCPTT groups except thesecond MCPTT user.

In a feasible implementation manner, the multi-group call setup messageincludes an identifier of a temporary group that includes the N MCPTTgroups, and the first MCPTT server is an MCPTT server of the temporarygroup.

Optionally, when receiving the multi-group call setup message sent bythe second UE, the transceiver unit 12 is configured to receive themulti-group call setup message that is sent by the second UE and that isforwarded by an MCPTT server of the second MCPTT user.

Optionally, before the transceiver unit 12 sends the call message to thefirst UE, the processing unit 11 is further configured to obtaininformation about the temporary group according to the identifier of thetemporary group.

The information about the temporary group includes the identifier of thetemporary group and identifiers of the N MCPTT groups.

Optionally, the information about the temporary group further includesinformation about an MCPTT user in at least one of the N MCPTT groups.

In another feasible implementation manner, the multi-group call setupmessage includes identifiers of the N MCPTT groups.

The first MCPTT server is an MCPTT server of the second MCPTT user.

Optionally, before the transceiver unit 12 sends the call message to thefirst UE, the processing unit 11 is further configured to obtaininformation about an MCPTT user in at least one of the N MCPTT groupsaccording to the identifiers of the N MCPTT groups.

Optionally, when the transceiver unit 12 sends the call message to thefirst UE, the following optional implementation solutions may be used.

In a first optional implementation solution, when sending the callmessage to the first UE, the transceiver unit 12 is configured to send afirst paging message to the first UE.

The first paging message is used to page the first UE to join themulti-group call, so that the first UE joins the multi-group callaccording to the first paging message.

In a second optional implementation solution, when sending the callmessage to the first UE, the transceiver unit 12 is configured to send asecond paging message to an MCPTT server of the first MCPTT user.

The second paging message is used to page the first UE to join themulti-group call, so that the MCPTT server of the first MCPTT user sendsa third paging message to the first UE, and the first UE joins themulti-group call according to the third paging message.

In a third optional implementation solution, when sending the callmessage to the first UE, the transceiver unit 12 is configured to send afourth paging message to an MCPTT server of an MCPTT group to which thefirst MCPTT user belongs.

The fourth paging message is used to page the first UE to join themulti-group call, so that the MCPTT server of the MCPTT group to whichthe first MCPTT user belongs sends a fifth paging message to the firstUE or sends a fifth paging message to the first UE by using an MCPTTserver of the first MCPTT user, and the first UE joins the multi-groupcall according to the fifth paging message, where the fifth pagingmessage is used to page the first UE to join the multi-group call.

In a fourth optional implementation solution, when sending the callmessage to the first UE, the transceiver unit 12 is configured to send afirst notification message to the first UE.

The first notification message includes a session identifier of themulti-group call, and the first notification message is used to instructthe first UE to join the multi-group call according to the sessionidentifier, so that the first UE joins the multi-group call according tothe session identifier.

In a fifth optional implementation solution, when sending the callmessage to the first UE, the transceiver unit 12 is configured to send asecond notification message to an MCPTT server of the first MCPTT user.

The second notification message includes a session identifier of themulti-group call, and the second notification message is used toinstruct the first UE to join the multi-group call according to thesession identifier, so that the MCPTT server of the first MCPTT usersends a third notification message to the first UE, where the thirdnotification message includes the session identifier, and the thirdnotification message is used to instruct the first UE to join themulti-group call according to the session identifier, so that the firstUE joins the multi-group call according to the session identifier.

In a sixth optional implementation solution, when sending the callmessage to the first UE, the transceiver unit 12 is configured to send afourth notification message to an MCPTT server of an MCPTT group towhich the first MCPTT user belongs.

The fourth notification message includes a session identifier of themulti-group call, and the fourth notification message is used toinstruct the first UE to join the multi-group call according to thesession identifier, so that the MCPTT server of the MCPTT group to whichthe first MCPTT user belongs sends a fifth notification message to thefirst UE or sends a fifth notification message to the first UE by usingan MCPTT server of the first MCPTT user, and the first UE joins themulti-group call according to the session identifier.

The MCPTT server in this embodiment may be configured to execute thetechnical solutions executed by the first MCPTT server in the foregoingmethod embodiments of the present invention. Implementation principlesthereof are similar, and details are not described herein.

In this embodiment, a processing unit 11 of an MCPTT server determinesto set up a multi-group call involving N MCPTT groups, and a transceiverunit 12 of the MCPTT server sends a call message to first UE, so thatthe first UE joins the multi-group call according to the call message,where a first MCPTT user is an associated user of the first UE, and thefirst MCPTT user is any MCPTT user in the N MCPTT groups. In this way,the multi-group call can be performed among the N MCPTT groups.

FIG. 8 is a schematic structural diagram of a first embodiment of UEaccording to the present invention. As shown in FIG. 8, the UE in thisembodiment serves as first UE and may include a transceiver unit 21 anda processing unit 22.

The transceiver unit 21 is configured to receive a call message, wherethe call message is used to add the first UE to a multi-group callinvolving N MCPTT groups.

N is an integer greater than or equal to 2, a first MCPTT user is anassociated user of the first UE, and the first MCPTT user is any MCPTTuser in the N MCPTT groups.

The processing unit 22 is configured to join the multi-group callaccording to the call message.

Optionally, when receiving the call message, the transceiver unit 21 isconfigured to receive a notification message, where the notificationmessage includes a session identifier of the multi-group call.

The notification message is used to instruct the first UE to join themulti-group call according to the session identifier.

When joining the multi-group call according to the call message, theprocessing unit 22 is configured to join the multi-group call accordingto the session identifier.

Optionally, the multi-group call involving the N MCPTT groups isinitiated by a second MCPTT user.

The first MCPTT user is any MCPTT user in the N MCPTT groups except thesecond MCPTT user.

Optionally, when receiving the call message, the transceiver unit 21 isconfigured to receive the call message that is sent by an MCPTT serverof an MCPTT group to which the first MCPTT user belongs; or receive thecall message that is sent by an MCPTT server of the first MCPTT user; orreceive the call message that is sent by an MCPTT server of a temporarygroup that includes the N MCPTT groups.

Optionally, when receiving the call message, the transceiver unit 21 isconfigured to receive the call message that is sent by an MCPTT serverof the second MCPTT user.

The UE in this embodiment may be configured to execute the technicalsolutions executed by the first UE in the foregoing method embodimentsof the present invention. Implementation principles thereof are similar,and details are not described herein.

In this embodiment, a transceiver unit 21 of UE receives a call message,where the call message is used to add the first UE to a multi-group callinvolving N MCPTT groups; and then, a processing unit 22 of the UE joinsthe multi-group call according to the call message. In this way, themulti-group call can be performed among the N MCPTT groups.

FIG. 9 is a schematic structural diagram of a second embodiment of UEaccording to the present invention. As shown in FIG. 9, the UE in thisembodiment serves as second UE and may include a processing unit 31 anda transceiver unit 32.

The processing unit 31 is configured to generate a multi-group callsetup message, where the multi-group call setup message is used by asecond MCPTT user to request a first MCPTT server to set up amulti-group call involving N MCPTT groups.

N is an integer greater than or equal to 2, the second MCPTT user is anassociated user of the second UE, and an MCPTT group to which the secondMCPTT user belongs is at least one of the N MCPTT groups.

The transceiver unit 32 is configured to send the multi-group call setupmessage to the first MCPTT server.

In a feasible implementation manner, the multi-group call setup messageincludes an identifier of a temporary group that includes the N MCPTTgroups.

The first MCPTT server is an MCPTT server of the temporary group.

Optionally, when sending the multi-group call setup message to the firstMCPTT server, the transceiver unit 32 is configured to send themulti-group call setup message to the first MCPTT server by using anMCPTT server of the second MCPTT user.

Optionally, the processing unit 31 is further configured to create thetemporary group before the transceiver unit 32 sends the multi-groupcall setup message to the first MCPTT server.

In another feasible implementation manner, the multi-group call setupmessage includes identifiers of the N MCPTT groups.

The first MCPTT server is an MCPTT server of the second MCPTT user.

The UE in this embodiment may be configured to execute the technicalsolutions executed by the second UE in the foregoing method embodimentsof the present invention. Implementation principles thereof are similar,and details are not described herein.

In this embodiment, a processing unit 31 of UE generates a multi-groupcall setup message, and a transceiver unit 32 of the UE sends themulti-group call setup message to a first MCPTT server, where themulti-group call setup message is used by a second MCPTT user to requestthe first MCPTT server to set up a multi-group call involving N MCPTTgroups, so that the first MCPTT server can send a call message to firstUE (where an associated user of the first UE is any MCPTT user in the NMCPTT groups except the second MCPTT user), and the first UE joins themulti-group call. In this way, the multi-group call can be performedamong the N MCPTT groups.

FIG. 10 is a schematic structural diagram of a second embodiment of anMCPTT server according to the present invention. As shown in FIG. 10,the MCPTT server in this embodiment serves as a first MCPTT server andmay include a processor 41 and a transceiver 42.

The processor 41 is configured to determine to set up a multi-group callinvolving N MCPTT groups, where N is an integer greater than or equal to2.

The transceiver 42 is configured to send a call message to first userequipment UE, where the call message is used to add the first UE to themulti-group call.

A first MCPTT user is an associated user of the first UE, and the firstMCPTT user is any MCPTT user in the N MCPTT groups.

Optionally, before the processor 41 determines to set up the multi-groupcall involving the N MCPTT groups, the transceiver 42 is furtherconfigured to receive a multi-group call setup message sent by secondUE, where the multi-group call setup message is used by a second MCPTTuser to request the first MCPTT server to set up the multi-group callinvolving the N MCPTT groups.

The second MCPTT user is an associated user of the second UE, and anMCPTT group to which the second MCPTT user belongs is at least one ofthe N MCPTT groups.

When determining to set up the multi-group call involving the N MCPTTgroups, the processor 41 is configured to determine, according to themulti-group call setup message, to set up the multi-group call.

The first MCPTT user is any MCPTT user in the N MCPTT groups except thesecond MCPTT user.

In a feasible implementation manner, the multi-group call setup messageincludes an identifier of a temporary group that includes the N MCPTTgroups.

The first MCPTT server is an MCPTT server of the temporary group.

Optionally, when receiving the multi-group call setup message sent bythe second UE, the transceiver 42 is configured to:

receive the multi-group call setup message that is sent by the second UEand that is forwarded by an MCPTT server of the second MCPTT user.

Optionally, before the transceiver 42 sends the call message to thefirst UE, the processor 41 is further configured to obtain informationabout the temporary group according to the identifier of the temporarygroup.

The information about the temporary group includes the identifier of thetemporary group and identifiers of the N MCPTT groups.

Optionally, the information about the temporary group further includesinformation about an MCPTT user in at least one of the N MCPTT groups.

In another feasible implementation manner, the multi-group call setupmessage includes identifiers of the N MCPTT groups.

The first MCPTT server is an MCPTT server of the second MCPTT user.

Optionally, before the transceiver 42 sends the call message to thefirst UE, the processor 41 is further configured to obtain informationabout an MCPTT user in at least one of the N MCPTT groups according tothe identifiers of the N MCPTT groups.

Optionally, when the transceiver 42 sends the call message to the firstUE, the following optional implementation solutions may be used.

In a first optional implementation solution, when sending the callmessage to the first UE, the transceiver 42 is configured to send afirst paging message to the first UE.

The first paging message is used to page the first UE to join themulti-group call, so that the first UE joins the multi-group callaccording to the first paging message.

In a second optional implementation solution, when sending the callmessage to the first UE, the transceiver 42 is configured to send asecond paging message to an MCPTT server of the first MCPTT user.

The second paging message is used to page the first UE to join themulti-group call, so that the MCPTT server of the first MCPTT user sendsa third paging message to the first UE, and the first UE joins themulti-group call according to the third paging message.

In a third optional implementation solution, when sending the callmessage to the first UE, the transceiver 42 is configured to send afourth paging message to an MCPTT server of an MCPTT group to which thefirst MCPTT user belongs.

The fourth paging message is used to page the first UE to join themulti-group call, so that the MCPTT server of the MCPTT group to whichthe first MCPTT user belongs sends a fifth paging message to the firstUE or sends a fifth paging message to the first UE by using an MCPTTserver of the first MCPTT user, and the first UE joins the multi-groupcall according to the fifth paging message, where the fifth pagingmessage is used to page the first UE to join the multi-group call.

In a fourth optional implementation solution, when sending the callmessage to the first UE, the transceiver 42 is configured to send afirst notification message to the first UE.

The first notification message includes a session identifier of themulti-group call, and the first notification message is used to instructthe first UE to join the multi-group call according to the sessionidentifier, so that the first UE joins the multi-group call according tothe session identifier.

In a fifth optional implementation solution, when sending the callmessage to the first UE, the transceiver 42 is configured to send asecond notification message to an MCPTT server of the first MCPTT user.

The second notification message includes a session identifier of themulti-group call, and the second notification message is used toinstruct the first UE to join the multi-group call according to thesession identifier, so that the MCPTT server of the first MCPTT usersends a third notification message to the first UE, where the thirdnotification message includes the session identifier, and the thirdnotification message is used to instruct the first UE to join themulti-group call according to the session identifier, so that the firstUE joins the multi-group call according to the session identifier.

In a sixth optional implementation solution, when sending the callmessage to the first UE, the transceiver 42 is configured to send afourth notification message to an MCPTT server of an MCPTT group towhich the first MCPTT user belongs.

The fourth notification message includes a session identifier of themulti-group call, and the fourth notification message is used toinstruct the first UE to join the multi-group call according to thesession identifier, so that the MCPTT server of the MCPTT group to whichthe first MCPTT user belongs sends a fifth notification message to thefirst UE or sends a fifth notification message to the first UE by usingan MCPTT server of the first MCPTT user, and the first UE joins themulti-group call according to the session identifier.

The MCPTT server in this embodiment may be configured to execute thetechnical solutions executed by the first MCPTT server in the foregoingmethod embodiments of the present invention. Implementation principlesthereof are similar, and details are not described herein.

In this embodiment, a processor 41 of an MCPTT server determines to setup a multi-group call involving N MCPTT groups, and a transceiver 42 ofthe MCPTT server sends a call message to first UE, so that the first UEjoins the multi-group call according to the call message, where a firstMCPTT user is an associated user of the first UE, and the first MCPTTuser is any MCPTT user in the N MCPTT groups. In this way, themulti-group call can be performed among the N MCPTT groups.

FIG. 11 is a schematic structural diagram of a third embodiment of UEaccording to the present invention. As shown in FIG. 11, the UE in thisembodiment serves as first UE and may include a transceiver 51 and aprocessor 52.

The transceiver 51 is configured to receive a call message, where thecall message is used to add the first UE to a multi-group call involvingN MCPTT groups.

N is an integer greater than or equal to 2, a first MCPTT user is anassociated user of the first UE, and the first MCPTT user is any MCPTTuser in the N MCPTT groups.

The processor 52 is configured to join the multi-group call according tothe call message.

Optionally, when receiving the call message, the transceiver 51 isconfigured to receive a notification message, where the notificationmessage includes a session identifier of the multi-group call.

The notification message is used to instruct the first UE to join themulti-group call according to the session identifier.

When joining the multi-group call according to the call message, theprocessor 52 is configured to join the multi-group call according to thesession identifier.

Optionally, the multi-group call involving the N MCPTT groups isinitiated by a second MCPTT user.

The first MCPTT user is any MCPTT user in the N MCPTT groups except thesecond MCPTT user.

Optionally, when receiving the call message, the transceiver 51 isconfigured to receive the call message that is sent by an MCPTT serverof an MCPTT group to which the first MCPTT user belongs; or receive thecall message that is sent by an MCPTT server of the first MCPTT user; orreceive the call message that is sent by an MCPTT server of a temporarygroup that includes the N MCPTT groups.

Optionally, when receiving the call message, the transceiver 51 isconfigured to receive the call message that is sent by an MCPTT serverof the second MCPTT user.

The UE in this embodiment may be configured to execute the technicalsolutions executed by the first UE in the foregoing method embodimentsof the present invention. Implementation principles thereof are similar,and details are not described herein.

In this embodiment, a transceiver 51 of UE receives a call message,where the call message is used to add the first UE to a multi-group callinvolving N MCPTT groups; and then, a processor 52 of the UE joins themulti-group call according to the call message. In this way, themulti-group call can be performed among the N MCPTT groups.

FIG. 12 is a schematic structural diagram of a fourth embodiment of UEaccording to the present invention. As shown in FIG. 12, the UE in thisembodiment serves as second UE and may include a processor 61 and atransceiver 62.

The processor 61 is configured to generate a multi-group call setupmessage, where the multi-group call setup message is used by a secondMCPTT user to request a first MCPTT server to set up a multi-group callinvolving N MCPTT groups.

N is an integer greater than or equal to 2, the second MCPTT user is anassociated user of the second UE, and an MCPTT group to which the secondMCPTT user belongs is at least one of the N MCPTT groups.

The transceiver 62 is configured to send the multi-group call setupmessage to the first MCPTT server.

In a feasible implementation manner, the multi-group call setup messageincludes an identifier of a temporary group that includes the N MCPTTgroups.

The first MCPTT server is an MCPTT server of the temporary group.

Optionally, when sending the multi-group call setup message to the firstMCPTT server, the transceiver 62 is configured to send the multi-groupcall setup message to the first MCPTT server by using an MCPTT server ofthe second MCPTT user.

Optionally, the processor 61 is further configured to create thetemporary group before the transceiver 62 sends the multi-group callsetup message to the first MCPTT server.

In another feasible implementation manner, the multi-group call setupmessage includes identifiers of the N MCPTT groups.

The first MCPTT server is an MCPTT server of the second MCPTT user.

The UE in this embodiment may be configured to execute the technicalsolutions executed by the second UE in the foregoing method embodimentsof the present invention. Implementation principles thereof are similar,and details are not described herein.

In this embodiment, a processor 61 of UE generates a multi-group callsetup message, and a transceiver 62 of the UE sends the multi-group callsetup message to a first MCPTT server, where the multi-group call setupmessage is used by a second MCPTT user to request the first MCPTT serverto set up a multi-group call involving N MCPTT groups, so that the firstMCPTT server can send a call message to first UE (where an associateduser of the first UE is any MCPTT user in the N MCPTT groups except thesecond MCPTT user), and the first UE joins the multi-group call. In thisway, the multi-group call can be performed among the N MCPTT groups.

Persons of ordinary skill in the art may understand that all or some ofthe steps of the foregoing method embodiments may be implemented by aprogram instructing relevant hardware. The foregoing program may bestored in a computer readable storage medium. When the program runs, thesteps of the foregoing method embodiments are performed. The foregoingstorage medium includes: any medium that can store program code, such asa read-only memory (ROM for short), a random access memory (RAM forshort), a magnetic disk, or an optical disc.

Finally, it should be noted that the foregoing embodiments are merelyintended for describing the technical solutions of the presentinvention, but not for limiting the present invention. Although thepresent invention is described in detail with reference to the foregoingembodiments, persons of ordinary skill in the art should understand thatthey may still make modifications to the technical solutions describedin the foregoing embodiments or make equivalent replacements to some orall technical features thereof, without departing from the scope of thetechnical solutions of the embodiments of the present invention.

What is claimed is:
 1. A multi-group call setup method, comprising:receiving, by a first mission critical push to talk (MCPTT) server of atemporary group comprising N MCPTT groups, a multi-group call setupmessage sent from a second user equipment (UE), wherein a second MCPTTuser is an associated user of the second UE, and the second MCPTT useris a MCPTT user in one of the N MCPTT groups, wherein the multi-groupcall setup message comprises an identifier of the temporary group;determining, by the first MCPTT server, to set up a multi-group callinvolving the N MCPTT groups, wherein N is an integer greater than orequal to 2; and sending, by the first MCPTT server, a call message to aUE, wherein the call message is used to add the first UE to themulti-group call, wherein a first MCPTT user is an associated user ofthe first UE, and wherein the first MCPTT user is an MCPTT user in the NMCPTT groups; wherein the sending the call message to the first UEcomprises sending, by the first MCPTT server, a first paging message toa MCPTT server of a MCPTT group to which the first MCPTT user belongsaccording to an identifier of the MCPTT group to which the first MCPTTuser belongs, wherein the first paging message causes the MCPTT serverof the MCPTT group to which the first MCPTT user belongs to send asecond paging message to the first UE to page the first UE to join themulti-group call, and wherein the first paging message comprises theidentifier of the temporary group.
 2. The method according to claim 1,wherein the determining, by a first MCPTT server, to set up amulti-group call involving N MCPTT groups comprises: determining, by thefirst MCPTT server according to the multi-group call setup message, toset up the multi-group call, wherein the first MCPTT user is any MCPTTuser in the N MCPTT groups other than the second MCPTT user.
 3. Amulti-group call setup method, comprising: receiving, by a first userequipment (UE), a call message, wherein the call message is used to addthe first UE to a multi-group call involving N mission critical push totalk (MCPTT) groups, wherein N is an integer greater than or equal to 2,wherein a first MCPTT user is an associated user of the first UE, andwherein the first MCPTT user is an MCPTT user in the N MCPTT groups; andjoining, by the first UE, the multi-group call according to the callmessage; wherein the receiving the call message comprises receiving, bythe first UE, a notification message, wherein the notification messagecomprises a session identifier of the multi-group call, and wherein thenotification message instructs the first UE to join the multi-group callaccording to the session identifier; and wherein the joining themulti-group call according to the call message comprises joining, by thefirst UE, the multi-group call according to the session identifier.
 4. Amission critical push to talk (MCPTT) server of a temporary groupcomprising N MCPTT groups, comprising: a transceiver, configured toreceive a multi-group call setup message from a second user equipment(UE), wherein a second MCPTT user is an associated user of the secondUE, wherein the second MCPTT user is a MCPTT user in an MCPTT group ofthe N MCPTT groups, and wherein the multi-group call setup messagecomprises an identifier of the temporary group; a processor; and anon-transitory computer-readable storage medium storing a program to beexecuted by the processor, the program including instructions to:determine to set up a multi-group call involving the N MCPTT groups,wherein N is an integer greater than or equal to 2; and cause thetransceiver to send a call message to a first UE, wherein the callmessage is used to add the first UE to the multi-group call, wherein afirst MCPTT user is an associated user of the first UE, and wherein thefirst MCPTT user is an MCPTT user in the N MCPTT groups; wherein programfurther includes instructions to cause the transceiver to send, inresponse to sending the call message to the first UE, a first pagingmessage to a MCPTT server of a MCPTT group to which the first MCPTT userbelongs according to an identifier of the MCPTT group to which the firstMCPTT user belongs, wherein the first paging message causes the MCPTTserver of the MCPTT group to which the first MCPTT user belongs to senda second paging message to the first UE to page the first UE to join themulti-group call, and wherein the first paging message comprises theidentifier of the temporary group.
 5. The MCPTT server according toclaim 4, wherein the program further includes instructions to determine,when determining to set up the multi-group call involving the N MCPTTgroups, according to the multi-group call setup message, to set up themulti-group call, wherein the first MCPTT user is an MCPTT user in the NMCPTT groups other than the second MCPTT user.
 6. User equipment (UE),serving as a first UE, comprising: a transceiver, configured to receivea call message, wherein the call message is used to add the first UE toa multi-group call involving N mission critical push to talk (MCPTT)groups, N is an integer greater than or equal to 2, a first MCPTT useris an associated user of the first UE, and the first MCPTT user is anyMCPTT user in the N MCPTT groups; a processor; and a non-transitorycomputer-readable storage medium storing a program to be executed by theprocessor, the program including instructions to: join the multi-groupcall according to the call message; wherein the transceiver is furtherconfigured to receive a notification message when receiving the callmessage, wherein the notification message comprises a session identifierof the multi-group call, and wherein the notification message instructsthe first UE to join the multi-group call according to the sessionidentifier; and wherein the program further includes instructions tojoin the multi-group call according to the session identifier whenjoining the multi-group call according to the call message.
 7. The UEaccording to claim 6, wherein the multi-group call involving the N MCPTTgroups is initiated by a second MCPTT user, and wherein the first MCPTTuser is an MCPTT user in the N MCPTT groups other than the second MCPTTuser.
 8. The UE according to claim 6, wherein the transceiver is furtherconfigured to perform, when receiving the call message, at least one of:receive the call message that is sent by an MCPTT server of an MCPTTgroup to which the first MCPTT user belongs; or receive the call messagethat is sent by an MCPTT server of the first MCPTT user; or receive thecall message that is sent by an MCPTT server of a temporary group thatcomprises the N MCPTT groups.